title: Permanent Neonatal Diabetes and Enteric Anendocrinosis Associated With Biallelic Mutations in NEUROG3.
abstract: OBJECTIVE
  NEUROG3 plays a central role in the development of both pancreatic islets and enteroendocrine cells. Homozygous hypomorphic missense mutations in NEUROG3 have been recently associated with a rare form of congenital malabsorptive diarrhea secondary to enteroendocrine cell dysgenesis. Interestingly, the patients did not develop neonatal diabetes but childhood-onset diabetes. We hypothesized that null mutations in NEUROG3 might be responsible for the disease in a patient with permanent neonatal diabetes and severe congenital malabsorptive diarrhea.
  
  
  METHODS
  The single coding exon of NEUROG3 was amplified and sequenced from genomic DNA. The mutant protein isoforms were functionally characterized by measuring their ability to bind to an E-box element in the NEUROD1 promoter in vitro and to induce ectopic endocrine cell formation and cell delamination after in ovo chicken endoderm electroporation.
  
  
  RESULTS
  Two different heterozygous point mutations in NEUROG3 were identified in the proband [c.82G>T (p.E28X) and c.404T>C (p.L135P)], each being inherited from an unaffected parent. Both in vitro and in vivo functional studies indicated that the mutant isoforms are biologically inactive. In keeping with this, no enteroendocrine cells were detected in intestinal biopsy samples from the patient.
  
  
  CONCLUSIONS
  Severe deficiency of neurogenin 3 causes a rare novel subtype of permanent neonatal diabetes. This finding confirms the essential role of NEUROG3 in islet development and function in humans.
authors.affiliation: Institute of Biomedical and Clinical Science, Peninsula Medical School, Exeter, UK.
authors.forename: Oscar
authors.initials: O
authors.lastname: Rubio-Cabezas
authors.forename: Jan N
authors.initials: JN
authors.lastname: Jensen
authors.forename: Maria I
authors.initials: MI
authors.lastname: Hodgson
authors.forename: Ethel
authors.initials: E
authors.lastname: Codner
authors.forename: Sian
authors.initials: S
authors.lastname: Ellard
authors.forename: Palle
authors.initials: P
authors.lastname: Serup
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Hattersley
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics*; D002642:Chick Embryo; D004252:DNA Mutational Analysis; D003920:Diabetes Mellitus / Q000235:genetics*; D018274:Electroporation; D019858:Enteroendocrine Cells; D005091:Exons / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics*; D017354:Point Mutation / Q000235:genetics; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms / Q000235:genetics
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; C498695:NEUROG3 protein, human